1. Field of the Invention
The present invention relates to an alarm device for a vehicle for detecting an object that approaches the vehicle and generating an alarm.
2. Description of the Background Art
For accident avoidance during vehicle travel, an alarm device is conventionally known that includes a distance measuring sensor mounted on a vehicle to detect obstacles around the vehicle and alert the driver to approach of the obstacles. A conventional alarm device known includes a reckless overtaking alarm device as disclosed in Japanese Patent Application Laid-Open No. 54-118036 (1979), which monitors a slanting rear direction of a direction to which a driver intends to make a lane change, to detect the following vehicle in that direction. This alarm device detects an instruction operation for lane change, determines whether the following vehicle is within a prescribed region when the instruction operation is present, and generates an alarm to inform that overtaking is dangerous based on the determination result.
Japanese Patent Application Laid-Open No. 2000-233699 proposes another alarm device that recognizes a vehicle traveling state based on a steering angle, yaw rate, navigation information, etc., and detects objects in a direction appropriate to the traveling state, thus generating an alarm when obstacles are detected around the vehicle.
Japanese Patent Application Laid-Open Nos. 2002-274303 and 8-293099 (1996) also disclose techniques for an alarm device for a vehicle.
The above alarm devices disclosed in JP 54-118036 (1979) and JP 2000-233699 generate an alarm for all objects that are present in a fixed distance range from the vehicle. Accordingly, an alarm is generated not only for objects for which an alarm needs to be generated, such as a rearwardly approaching vehicle or a vehicle remaining in a blind spot region of the driver, but for objects for which an alarm does not need to be generated, such as a forwardly approaching stationary object including roadside street lamps and poles (hereinafter referred to as a “forwardly approaching stationary object”) or a forwardly approaching vehicle on the opposite lane, which annoys the driver.